Significance of Direct and Indirect Impacts of Temperature Increase Driven by Climate Change on Threat to Oilseed Rape Posed by Sclerotinia sclerotiorum

Sclerotinia stem rot, caused by Sclerotinia sclerotiorum, threatens oilseed rape (Brassica napus) crops internationally. The development of this disease is strongly controlled by the weather, which is why global climate change is likely to influence its spread and impact. Climate change may affect the pathogen directly or indirectly via the host plant. This study investigates the potential impact of climate warming on Sclerotinia stem rot severity in oilseed rape in Poland. The aim of this investigation was to assess the relationship between the direct impact (DI) and indirect impact (II) of climate change on disease severity using the 4.5 and 8.5 representative concentration pathways (RCPs). Under the RCP4.5 scenario, nearly 60% of the simulations performed for 16 regions in four periods (2020–2039, 2040–2059, 2060–2079, 2080–2099) showed reductions in disease severity in comparison to those conducted for 1986–2005, while under RCP 8.5, this reduction was generated for nearly 90% of the cases. The effect of the RCP scenario on clustering the regions according to the value of Sclerotinia stem rot severity was also investigated. The simulations revealed that, for all periods, the lowest disease severities are expected for Zachodniopomorskie and Pomorskie. The results obtained also show the superior effects of the II over the DI on Sclerotinia stem rot severity in the future. Under the RCP4.5 scenario, the rate of IIs was greater than that of DIs for 10 regions, while under RCP8.5, this relationship was registered for 16 regions. These outcomes result from the acceleration of the oilseed rape flowering period triggered by expected temperature increases. The novelty of this study lies in a detailed analysis of the relationships between the DI and II of climate change, expressed numerically, for 16 regions in Poland. The obtained results highlight the role of the indirect impact in shaping disease severity and indicate that it should be incorporated into assessment methods of climate change effects alongside the direct impact.

One of the most destructive and harmful diseases of oilseed rape is Sclerotinia stem rot, which is caused by Sclerotinia sclerotiorum [6].Among the 10 most significant biotic threats to oilseed rape cultivation, this pathogen holds first place in China and second in Australia, Europe, and Canada [7].
Yield losses due to Sclerotinia stem rot have been reported to be as high as 80% in China [8] and 75% in Nepal [9].In the United Kingdom, oilseed rape infestation by S. sclerotiorum results in a 50% yield loss [10], while in Germany, it results in a 20-30% yield loss [11].In Saskatchewan, Canada, and in Minnesota and North Dakota, USA, in 1991-1997, yield losses due to Sclerotinia stem rot ranged from 11.4 to 14.9%, ref. [12], 11.2 to 13.2%, and 5 to 13% [13], respectively.Also, in Poland, along with Phoma lingam and clubroot, Sclerotinia stem rot is considered to be among the most dangerous oilseed rape diseases [14].According to Starzycki and Starzycka, this disease occurs in Poland every year to a greater or lesser extent [15].In an experiment conducted in the years of 2005-2009 focusing on oilseed rape infestation by S. sclerotiorum, Jajor et al. registered 3-27% of the surveyed plants as having symptoms of the disease [16].Great diversity in the number of oilseed rape plants infested with S. sclerotiorum was found by Kaczmarek et al. and Bracharczyk et al., who, in the years of 2010-2011, observed that 2-34% and 25-50% of plants, respectively, had Sclerotinia stem rot [17,18].The importance of this disease is even better characterized by the results of research on its impact on the yield of oilseed rape.In a study on the optimization of the dates of fungicidal treatments against Sclerotinia stem rot in oilseed rape, Bracharczyk et al. [18] recorded yield losses of 6% and 19%, depending on the year.High yield losses of oilseed rape caused by S. sclerotiorum were also registered by Jajor et al. [16].While examining the impacts of fungicide protection and meteorological conditions on the infection of oilseed rape cultivars by S. sclerotiorum, the authors observed yield losses of up to 15%.According to Starzycki and Starzycka, yield losses may even exceed 30% under conditions that are extremely favorable for the development of the pathogen [15].
S. sclerotiorum survives in the soil as sclerotia from previous epidemics [19].Sclerotia germinate either myceliogenically, by producing mycelia, or carpogenically, by producing apothecia, which, in turn, release ascospores [20].The infection of oilseed rape leaves by S. sclerotiorum occurs primarily as a result of ascospore germination on petals, through which the mycelium of the pathogen penetrates into the leaf tissue [21,22].When ascospores come into direct contact with leaf tissue, they either do not germinate [22] or their ability to germinate is strongly reduced [23].A strong correlation between petal infestation and disease incidence explains why the flowering period of oilseed rape is critical for the epidemiology of Sclerotinia stem rot [22,24].
The development of this disease is also affected by meteorological factors, among which air temperature, in addition to air humidity, is commonly considered to be a major determinant of Sclerotinia stem rot risk [25][26][27].Knowledge about the relationship between temperature and pathogen development is widely used to predict the disease threat to crops as a result of climate change [28][29][30].
According to the Synthesis Report of the IPCC, in the first two decades of the 21st century, the global surface temperature was 0.99 • C higher than in 1850-1900, and it has increased faster since 1970 than in any other 50-year period over at least the last 2000 years [31].Depending on the scenario, in 2081-2100, the Earth's surface temperature is very likely to have increased by an average of 1.4 • C to 4.4 • C compared to that in 1850-1900.
Such changes in temperature could profoundly alter pathogen threats to crops in the future [32][33][34].The status of crop diseases may be affected by climate change directly or indirectly [35].The direct impact of climate change results from the immediate reactions of living organisms to changed meteorological conditions, while the indirect results come from changes in the compositions, structures, and functions of ecosystems triggered by changes in meteorological variables [36].
In the present article, a direct impact (DI) is a relationship between temperature and S. sclerotiorum development, while an indirect impact (II) represents the influence of temperature on the development of oilseed rape-the S. sclerotiorum's host crop.The complex nature of the influence of climate change on crop disease development makes it difficult to precisely define relationships between DIs and IIs.For this reason, despite the general agreement on the distinction between these two methods of climate change impacts, it is not easy to find articles that deal with plant disease in which the relationships between the DI and II are expressed in numbers.Among the crops most often taken into account, in the last twenty years, the studies describing pathogen responses to climate change on the basis of simulation results have mostly included wheat, followed by rice, grapevine, and potato, whereas oilseed rape is under-represented [37].
The present work intends to fill the gap in information about the relationships between S. sclerotiorum and oilseed rape development under climate change conditions.We are especially interested in the relationships between the DI and II of climate change at the level of Sclerotinia stem rot risk.Our earlier studies indicated the superiority of the II over the DI in determining the fatty acid composition of oilseed rape oil on a national scale.We hypothesized that II may also be dominant in shaping the future Sclerotinia stem rot threat to oilseed rape.The objective of the present study was to check this hypothesis by comparing the DI and II of climate change on the level of Sclerotinia stem rot risk.We express the relationships between these phenomena numerically on the regional scale.The regions of Poland that are expected to experience major increases in S. sclerotiorum pressure on oilseed rape in the future are also indicated.

Development of a Model for Simulating the Flowering Time of Oilseed Rape
Our model was developed on the basis of data collected in field experiments conducted at Winna Góra (60 km south of Pozna ń) in 2005-2022.Each year, three oilseed rape cultivars were used in the study (Table 1).The data gathered in odd years were used to build the model, while model validation was performed on data from even years.

Year
The model development consisted of quantifying the relationship between the accumulated rapeseed developmental rate (ARDR) and the phenological development stages of the cultivars listed in Table 1, according to the BBCH scale [38].The phenological development stages were registered twice per week in the period from the first of January to the end of oilseed rape flowering period each year.Detailed information explaining how to calculate the rapeseed developmental rate (RDR) was presented by Racca et al. [39].The collected data were used to build a model simulating oilseed rape development.The model consisted of two submodels (Table 2).The first one describes oilseed rape development from 1 January to the beginning of flowering period (BBCH 61), while the second covers the period from the beginning to the end of flowering (BBCH 61-69) (Table 2).The validation of the model was based on a comparison of the simulated and observed results.The model was developed using the information collected by Koch and presented in her doctoral thesis [22].The data shown in this study illustrate the disease severity registered at different temperatures as an effect of the infection of oilseed rape stalks by ascospores.To mathematically describe the pathogen response to the stimulus, we used two submodels.Both define the effect of the temperature upon disease severity.The first, double logistic, operates in the range of 6-18 • C, while the second, based on the Beta function, operates in the range of 18-26 • C (Table 3).Table 3. Submodels used for the disease severity simulation.

Projection of the Effect of Climate Change on the Sclerotinia Stem Rot Severity in Oilseed Rape
The simulations were performed using two sets of meteorological data.The first consisted of data registered in the period of 1986-2005 at 133 locations in Poland (Figure 1).
The second was obtained after transforming the recorded data to reflect temperature changes under the RCP4.5 and RCP8.5 scenarios according to the 29 climate models presented on the Climate Change Knowledge Portal created by the World Bank (https://climateknowledgeportal.worldbank.org/download-data(accessed on 15 January 2023) (Table 4).
The transformation of meteorological data was conducted using the delta change approach, which consists of adding the mean monthly change value for the model results for the projected and registered periods to an observed time series according to Equation (1): where Tdb is the debiased temperature; Tobsref is the daily temperature observed in the reference period; Tsimproj is the monthly temperature simulated for the projected period; and Tsimref is the monthly temperature simulated for the reference period.The next task of the study was to estimate the effect of climate change on Sclerotinia stem rot severity in oilseed rape.This was completed using simulations of the impact of temperature on both pathogen development and the oilseed rape flowering period.This task was accomplished in three steps.The first step was to determine the dates of the beginning and the end of the oilseed rape flowering period (BBCH 61, BBCH 69).In the second step, the disease severity for each day of the flowering period was calculated.The third step consisted of calculating the sum of disease severity in the flowering period for each region (Dolnośl ąskie, Kujawsko-Pomorskie, Lubelskie, Lubuskie, Łódzkie, Małopolskie, Mazowieckie, Opolskie, Podkarpackie, Podlaskie, Pomorskie, Śl ąskie, Świętokrzyskie, Warmi ńsko-Mazurskie, Wielkopolskie, Zachodniopomorskie), scenario (RCP4.5,RCP8.The second was obtained after transforming the recorded data to reflect temperature changes under the RCP4.5 and RCP8.5 scenarios according to the 29 climate models presented on the Climate Change Knowledge Portal created by the World Bank (http://sdwebx.worldbank.org/climateportal/(accessed on 15 January 2023) (Table 4).Subsequently, we grouped the regions according to disease severity by applying a cluster analysis using the Euclidean distance in such a way that the connection level within the same group was as high as possible, whereas within combinations of other groups, it was as small as possible.Distinct groups of regions depending on disease severity were formed on the basis of the Euclidean distance equaling 1.0.
The next part of the study was designed to measure the impact of climate change on disease severity.To fulfill this task, in addition to the simulation results collected so far, information about disease severity for both the registered (1986-2005) and projected periods (2020-2039, 2040-2059, 2060-2079, 2080-2099) without the influence of temperature on oilseed rape flowering was needed.This is why another series of simulations was conducted.This time, the dates of oilseed rape flowering indicated for the period of 1986-2005 were also used in simulations for the other periods.On the basis of both simulation series, the impact of climate change on disease severity was calculated according to the equations presented below.
The direct impact of temperature on disease severity was calculated using Equation ( 2): where DI is the direct impact of climate change on disease severity; ds-tor i, j is the disease severity obtained from simulations without allowing for the influence of temperature on the development of oilseed rape for scenario i and period j (i: RCP4.5, RCP8.For further analysis, the accumulated rate of change (AROC) of the direct impact (DI) and indirect impact (II) of climate change over time was calculated using Equation ( 5): where AROC is the accumulated rate of change; Ii is the impact measured at period i; Ii + 1 is the impact measured at period i + 1; T is the time taken for that change to occur; and N is the total number of observations.

Development of a Model for Simulating the Flowering Time in Oilseed Rape
The submodels expressing the relationship between temperature and the oilseed rape flowering period are presented in Table 5.The comparison of the observed beginning of the oilseed rape flowering period and that simulated using the models developed revealed that the differences depending on the year did not exceed 9 days (Table 6).Even better results were obtained when we compared the observed and modeled ends of the flowering period.This time, the disagreement ranged between 1 and 7 days.The mean absolute error (MAE) obtained when we compared the simulated and observed start times of the flowering period, expressed in days of the year, was 4.6, while for the end of the flowering period, the MAE was 3.9.When the results of the beginning and end of the flowering period were put together, the differences between the observed and simulated results measured with the MAE was 4.3 (Figure 2), while the agreement between the observed and simulated results measured with R 2 was 0.88 (Figure 2).The model expressing the relationships between temperature and Sclerotinia stem rot severity consists of two submodels.The first one, double logistic, estimates the disease severity triggered by temperatures in the range of 6-18 • C, while the second is based on Beta functions in the range of 18-26 • C (Table 7).The relationship between the data and the model output is presented in Figure 3.

Development of a Model for Estimating Sclerotinia Stem Rot Severity in Oilseed Rape at Flowering Time
The model expressing the relationships between temperature and Sclerotinia stem rot severity consists of two submodels.The first one, double logistic, estimates the disease severity triggered by temperatures in the range of 6-18 °C, while the second is based on Beta functions in the range of 18-26 °C (Table 7).The relationship between the data and the model output is presented in Figure 3.The simulation based on meteorological data registered in the years of 1986-2005 generated average starts of the oilseed rape flowering stage, depending on the region analyzed, of between 122 (02.05 lubuskie) and 136 (16.05 małopolskie) days after 1 January (Table 8).For the RCP4.5 scenario, the simulation revealed reductions in the period from the 1st of January until the beginning of the flowering period of 8-13 (2020-2039), 11       The conducted simulations showed that, in the years of 1986-2005, the flowering period ended between 143 (26.05 lubuskie) and 157 (06.06 pomorskie) days after the 1st of January.In the simulations performed for the scenario of RCP4.
The results of clustering the regions on the basis of a Euclidean distance equal to 1.0 according to Sclerotinia stem rot severity are shown in Figure 4.Under the scenario of RCP4.5, irrespective of the period, the regions were grouped into three clusters.Three clusters were also distinguished under the RCP8.5 scenario for the periods of 2020-2039, 2040-2059, and 2060-2079, while for the period of 2080-2099, the regions were grouped into four clusters.Under the scenario of RCP4.5, the number of regions belonging to the cluster characterized by the smallest disease severity was two for 2020-2039 and 2040-2059, while it was three for the two other periods.The number of regions with the highest disease severity was nine for 2020-2039 and 2040-2059, while it was seven and eight, respectively, for 2060-2079 and 2080-2099.Under the RCP8.5 scenario, the number of regions with the smallest disease severity was two for 2020-2039, while it was three for the other periods.
The number of regions characterized by the highest disease severity was nine for 2020-2039 and 2040-2059, while it was eight and five for 2060-2079 and 2080-2099, respectively.The calculations showed systematic increases in the absolute values of both the DI and II of climate change on disease severity over time (Table 10).The minimum and maximum values of the DI under the RCP4.5 scenario were 1.62 in Łódzkie and 2.32 in Małopolskie, respectively, from 2020 to 2039, whereas they were 2.32 in Kujawsko-Pomorskie and 3.29 in Małopolskie, respectively, for 2040-2059 The analyzed parameter ranged between 2.88 in Łódzkie and 4.18 in Małopolskie for the period of 2060-2079 and 2.93 in Łódzkie and 4.46 in Małopolskie for 2080-2099.Under the RCP8.5 scenario, the calculation revealed that the minimum values of the DI were generated for Łódzkie (1.72 for 2020-2039, 2.44 for 2040-2059, 3.73 for 2060-2079, 4.64 for 2080-2099), irrespective of the period.The maximum values of that parameter were 2.28, 3.50, and 5.36 for Łódzkie for 2020-2039, 2040-2059, and 2060-2079, respectively, whereas the maximum value was 7.06 in Pomorskie for 2080-2099.The calculations that focused on the II of climate change under the RCP4.5 scenario revealed that the smallest values of that parameter were generated for Lubelskie: −1.60 (2020-2039), −2.17Under the RCP4.5 scenario, the AROCs of the II were greater over time than those expressing the rate of change in the DI for 10 regions (Dolnośl ąskie, Kujawsko-Pomorskie, Lubuskie, Łódzkie, Mazowieckie, Opolskie, Pomorskie, Warmi ńsko-Mazurskie, Wielkopolskie, Zachodniopomorskie), whereas under the RCP8.5 scenario, the AROCs of the II were greater than the opposite ones for all regions.For both scenarios, the maximum values of the AROCs of the DI and II were registered for Pomorskie (RCP4.5:0.108, 0.131; RCP8.5: 0.247, 0.322), while the minimum AROCs of the DI were found for Łódzkie (RCP4.5:0.066, RCP8.5: 0.146) and the minimum AROCs of the II were found for Lubelskie (RCP4.5:0.067, RCP8.5: 0.188)

Discussion
The present study focused on an exploration of the relationships between the direct impact and indirect impact of climate change on the level of Sclerotinia stem rot risk.On the basis of the meteorological data analyzed, we found that the flowering period of oilseed rape is expected to start and end earlier in the future, irrespective of the RCP scenario.In both scenarios, climate change affects the start date of the flowering period more than the end date.Moreover, these changes are dependent on the period.Over time, they will grow from the smallest for 2020-2039, reaching the highest values in 2080-2099.The simulation also revealed that the changes expected under the RCP8.5 scenario are greater than under RCP4.5 for all periods analyzed.
These findings are in agreement with the study results presented by Hájková et al. [40], who noticed a significant shift in the beginning of the oilseed rape flowering period.The authors demonstrated that the onset of flowering advanced progressively in the Czech Republic, and the differences between the start of that phenophase in 1991 and 2012 reached almost 15 days.Further studies of earlier-flowering plants in response to ongoing climate change have been registered in other European countries [41,42].For example, Parmesan and Yohe [43] confirmed this trend by analyzing the flowering periods of 461 plant species.According to Franks et al. [44], the shifts in phenophases are largely attributed to rising temperatures.In agreement with these findings, Hájková et al. [40] showed that the best predictor for the onset of oilseed rape flowering is the mean air temperature.The close relationship of oilseed rape flowering with this parameter was also demonstrated by Wójtowicz [45], who studied the effect of the mean air temperature registered in April on the start of that phenophase.The present study findings, which deal with the onset of flowering period, are also reflected by the results obtained in the studies performed with the use of models.Racca et al. [37] showed that the flowering of oilseed rape compared to the period of 1970-2000 is expected to start earlier, from 17-19 to 30-49 days for 2020-2055 and 2070-2100, respectively.
Our study demonstrated that the oilseed rape flowering period is expected to be prolonged in the future, mainly due to an earlier start of that phenophase under warming conditions.Similar conclusions were reached by Mo et al. [46], who analyzed data including 136 plant species from 217 observational sites across eight climatic zones in China from 1963 to 2013 and stated that flowering duration was prolonged, mainly because the beginning of flowering was more substantially advanced than the end of the flowering period.
The earlier start of the flowering period that was proven in the present study may implicate earlier infections of oilseed rape caused by S. sclerotiuorum.Confirmation of this thesis can be found in the work of Tiedman and Ulger [47], who stated that warming may enhance the infection window for this pathogen, in both the mid (2001-2030) and longer term (2071-2100), possibly leading to earlier infections in the future.
Our results also provide evidence for the effect of climate warming on the severity of Sclerotinia stem rot.This phenomenon is more dependent on the RCP scenario, while the influence of the locality appears to be smaller.Under the RCP4.5 scenario, nearly 60% of the simulations performed for 16 localities in four periods showed a reduction in disease severity in comparison to those registered for 1986-2005, while under RCP 8.5, this reduction was generated for nearly 90% of cases.These results are in agreement with the outcomes of Racca et al. [45], who, based on simulations, predicted a significant decrease in Sclerotinia infection risk, especially for the years of 2071-2100, for Lower Saxony in Germany.
In this study, we also presented the effect of the RCP scenario on the clustering of regions according to Sclerotinia stem rot severity.Under the RCP8.5 scenario, the clustering results appear to be more variable than under RCP4.5.However, under both scenarios, the lowest disease severity for all periods was generated for Zachodniopomorskie and Pomorskie.The results obtained indicate the need to adapt the protection of oilseed rape against S. sclerotiorum to regional conditions, reflecting the projected Sclerotinia stem rot severity for the region and period.
The future reduction in Sclerotinia stem rot severity presented in our study on the basis of the simulation outcomes results from the indirect impact of climate change.A comparison of the indirect impact and direct impact showed the superiority of the effect of the former over the latter on the Sclerotinia stem rot severity caused by climate warming in the future.Under the RCP4.5 scenario, the accumulated rate of change (AROC) for the indirect impact was greater than the AROC for the direct impact for 10 regions, while under RCP8.5, this relationship was registered for 16 regions.
The results obtained indicated the meaning of the indirect impact of climate change on the future threat to crops of pathogens and the necessity of taking this parameter into account when predicting outbreaks of plant diseases.
The complexity of climate change's effects on future pathogen risk has also been highlighted by others.For example, Madgwick et al. [48] analyzed the impact of climate change on Fusarium ear blight in the UK and proved the significance of incorporating a model of host plant development into the assessment of the pathogen risk.According to these authors, the date of wheat anthesis, i.e., the growth stage at which wheat is the most vulnerable to infection with Fusarium ear blight, is expected to appear earlier by about 11-15 days across the whole country in the 2020s and 2050s.Also, Evans et al. [49,50] and Butterworth et al. [51] demonstrated that the projection of crop epidemics triggered by climate change requires both crop and pathogen development to be taken into account.The present study demonstrates an extension of this approach and numerically expresses the relationships between the direct impact and indirect impact of climate change, which covers a knowledge gap in this field.Our results highlight the role of the indirect impact in shaping disease severity and indicate that, besides the direct impact, it should be incorporated into assessment methods of climate change effects.This approach enhances our ability to project the ongoing changes driven by global warming.We propose that the accelerated development of oilseed rape in the future, caused by climate change, will contribute to the mitigation of Sclerotinia stem rot.However, we are aware that the results presented in this work cannot be generalized, because they concern only one disease and one country.Further research involving further pathogens and climatic zones is required to establish the nature of the relationship between the direct impact and indirect impact of climate change.Focusing on this problem will help to answer the question of how agriculture can adapt to or mitigate ongoing climatic changes.In our earlier study, which focused on measuring the direct impact and indirect impact of climate change on the fatty acid composition in rapeseed oil, we analyzed the relationship between these phenomena on a national scale [52].This time, we described the relationship between the direct impact and indirect impact on a regional scale, which enabled us to present the problem more precisely.
In conclusion, it must be stressed that there are several uncertainties that impede the correct long-term projection of plant disease epidemics.Firstly, the development of the disease is influenced by many factors, among which, apart from the temperature, precipitation and humidity play very important roles.It must be pointed out that estimations of the rainfall distribution in a long time period are extremely difficult, if not impossible [37].It is also not easy to assess long-term breeding progress; hence, there is a lack of knowledge about the phenological development of future cultivars, and their resistance to pathogens makes it difficult to predict disease severity over a period of 100 years.Nevertheless, according to Wiens et al. [53], one should not worry too much about projection uncertainties, as the alternative would be to ignore future risks.Therefore, it is believed that crop disease risk simulations, although not perfect, are helpful for the development of strategies to mitigate the effect of climate change [37].

Conclusions
The obtained results indicate the need to take the indirect impact of climate change into account when estimating the threat posed by S. sclerotiorum to oilseed rape in the future.This approach is worth recommending when assessing the threat posed by other pathogens to other crops.The faster development of oilseed rape expected in the future

21 Figure 1 .
Figure 1.Spatial distribution of the 133 meteorological stations used in the study.

Figure 1 .
Figure 1.Spatial distribution of the 133 meteorological stations used in the study.
5; j: 2020-2039, 2040-2059, 2060-2079, 2080-2099); and ds1986-2005 is the disease severity obtained in simulations for the period of 1986-2005.The sum of the direct and indirect impacts of climate change on disease severity was calculated using Equation (3): (D + I)I = ds + tor i, j − ds1986-2005 (3) where (D + I)I is the sum of the direct and indirect impacts of climate change on disease severity; ds+tor i, j is the disease severity obtained in simulations allowing for the influence of temperature on the development of oilseed rape for scenario i and period j (i: RCP4.5, RCP8.5; j: 2020-2039, 2040-2059, 2060-2079, 2080-2099); and ds1986-2005 is the disease severity obtained in simulations for the period of 1986-2005.The indirect impact of climate change on disease severity was calculated using Equation (4): II = (D + I)I − DI (4) where II is the indirect impact of climate change on disease severity; (D + I)I is the sum of the direct and indirect impacts of climate change on disease severity; and DI is the direct impact of climate change on disease severity.

Figure 3 .
Figure 3.The effect of temperature on Sclerotinia stem rot severity (indicated by a red curve) and comparison of the observed and simulated values of that parameter (represented in the chart by a blue background).

Figure 3 .Table 8 .
Figure 3.The effect of temperature on Sclerotinia stem rot severity (indicated by a red curve) and comparison of the observed and simulated values of that parameter (represented in the chart by a blue background).Table 8.The reduction in time needed for the oilseed rape to start (BBCH 60) and end (BBCH 69) flowering and the duration of the flowering period predicted for the two scenarios (RCP4.5,RCP8.5) and four periods (2020-2039, 2040-2059, 2060-2079, 2080-2099) in comparison to those registered in the period of 1986-2005.

Figure 5 .
Figure 5. Charts: DI and II of climate change over time under the RCP4.5 scenario in 16 regions.Map: Distribution of the regions based on relationships between the AROCs of the DI and II on Sclerotinia stem rot severity under the RCP4.5 scenario.Red indicates AROC of DI > AROC of II; green indicates AROC of DI < AROC of II.

Figure 6 .
Figure 6.Charts: DI and II of climate change over time under the RCP85 scenario in 16 regions.Map: Distribution of regions based on relationships between the AROCs of the DI and II on Sclerotinia stem rot severity under the RCP8.5 scenario.Red indicates AROC of DI > AROC of II; green indicates AROC of DI < AROC of II.

Table 1 .
Cultivars used in the experiments aimed at model development.

Table 2 .
Submodels used for the simulation of the oilseed rape flowering period.

Table 4 .
List of climate models used in the study.

Earth
Science and Technology, Atmosphere and Ocean Research Institute (The University of Tokyo), and National Institute for Environmental Studies, Japan miroc-esm-chem Japan Agency for Marine-Earth Science and Technology, Atmosphere and Ocean Research Institute (The University of Tokyo), and National Institute for Environmental Studies, Japan

Table 4 .
List of climate models used in the study.
cesm1-bgc National Science Foundation, US Department of Energy, and National Center for Atmospheric Research, USA, and National Center for Atmospheric Research cesm1-cam5 National Center for Atmospheric Research, USA cmcc-cesm Euro-Mediterranean Center on Climate Change, Italia cmcc-cm Euro-Mediterranean Center on Climate Change, Italia cmcc-cms Euro-Mediterranean Center on Climate Change, Italia cnrm-cm5 Centre National de Recherches Météorologiques and Centre Européen de Recherche et de Formation Avancée, France

Table 5 .
Parameters of the submodels used for predicting the oilseed rape flowering period.

Table 6 .
Dates of the beginning and the end of the flowering period of oilseed rape cultivars.

Table 7 .
Parameters of the submodels used for estimating sclerotinia stem rot severity in oilseed rape at flowering time.

Table 7 .
Parameters of the submodels used for estimating sclerotinia stem rot severity in oilseed rape at flowering time.

Values of Coefficients in the Model Statistical Values p-Values R 2
Projection of the Effect of Climate Change on Sclerotinia Stem Rot Severity in Oilseed Rape 3.3.1.Simulation of the Effect of Climate Change on the Oilseed Rape Flowering Period